As will be appreciated by those skilled in the art, helical shaped devices include such items as the common screw and the like. In addition, specialized helical shaped devices such as screw conveyors are well known for the transport of various types of bulk material. Such conveyors generally include a helical shaped member which rotates within a housing or trough such that rotation of the screw conveyor along its longitudinal or central axis results in movement of the bulk material along the length of the device. In the past, such conveyors were typically constructed from metal, and each conveyor was specifically designed for a particular purpose and of the necessary length. However, although most prior art conveyors were specifically designed to meet a particular application, there have been some attempts at providing a modular type conveyor. Examples of U.S. patents which disclose such modular conveyors include U.S. Pat. No. 233,320 issued to A. L. Brewer on Oct. 19, 1888; U.S. Pat. No. 455,384 issued to H. Binkholz on July 7, 1891; U.S. Pat. No. 525,194 issued to J. Dyson, et al on Aug. 20, 1894; U.S. Pat. No. 546,879 issued to J. Dyson, et al on Sept. 24, 1895; U.S. Pat. No. 1,090,956 issued to W. J. Zinteck on Mar. 24, 1914; U.S. Pat. No. 1,867,573 issued to V. G. Leach on July 19, 1932; U.S. Pat. No. 2,394,163; U.S. Pat. No. 2,492,915 issued to A. B. Carlson on Dec. 27, 1949; U.S. Pat. No. 3,178,210; U.S. Pat. No. 3,648,826 issued to Dean P. Brooks on March 1972; and U.S. Pat. No. 3,705,644 issued to C. E. Kawchitch on Dec. 12, 1972.
Thus, a review of the prior art patents reveals that to date, only the Kawchitch patent shows a modular plastic screw conveyor, and none of the prior art including Kawchitch even suggests bonding a multiplicity of plastic modules axially to produce a unitary plastic screw conveyor of any desired length with a continuous flight member extending the length of the conveyor. Therefore, it is an object of this invention to provide a unitary plastic screw conveyor having an axial member of any selected length and having a continuous flight member helically enclosing the full length of the axial member.
It is still a further object of the present invention to provide a unitary screw conveyor of any selected length formed of a multiplicity of modules which may be joined axially and wherein the flight member extends around the axial member greater than 360.degree..
Other objects and advantages will be obvious, and will in part appear hereinafter, and will be accomplished by the present invention which provides a conveyor apparatus having a unitary plastic screw conveyor which includes an axial member extending a selected or desired length. A flight member helically encircles more than 360.degree. of the axial member and extends the length of the axial member.
The apparatus comprises a multiplicity of a substantially identical integrally molded plastic modules. Each of the modules includes an elongated axial member extending between a pair of ends and with a non-circular aperture which extends coaxially through the axial member. Each of the modules also includes a flight member which helically encircles nor more than 360.degree. of the axial member and which extends between the pair of ends. Each of the ends of the axial members are formed to cooperate with one of the ends of another module. The plastic screw conveyor is formed by coaxially aligning the multiplicity of modules end-to-end such that the end of one module is in contact with the end of another module and so that the non-circular aperture through the modules are in register. The ends of the multiplicity of modules which are in contact are permanently joined or bonded so as to form a unitary screw conveyor having an axial member which defines an elongated aperture of a non-circular cross-section extending the length of the axial member. The unitary screw conveyor also includes a continuous flight member which encircles more than 360.degree. of the axial member and which extends the length of the joined modules.
The screw conveyor formed of the multiplicity of permanently bonded modules is placed on a drive shaft which has a non-circular cross-section which may be substantially identical to the non-circular cross-section of the elongated aperture. Whether the drive shaft has an identical cross-section or not, it is received by and cooperate with the non-circular elongated aperture in a non-rotating manner such that rotation of the drive shaft causes rotation of the unitary screw conveyor. A drive means is provided for rotating the drive shaft.